Identify that noise (RB25)

[Gibson]

Car has developed an odd ... knock (reluctant to use that word because it scares me) at idle. Doesn't really get louder when revs increase, but definitely very noticeable at idle. Sounds like it's coming from near the back and bottom of the engine. Car runs and drives fine, no noticeable loss in power.

Just put new 5w40 synthetic in, same oil as I had before. I overfilled it a little but drained some out this morning. Noise is still there unfortunately. Thought about putting some Lucas Oil Stabilizer in?

I'll let the video do the talking, although it is more noticeable in person. I captured this lying right under the car. Most noticeable after the video's 12s mark.

http://www.flickr.com/photos/gibbyson4/9636065697/

[Skym]

Sounds normal to me. Lifters are maybe a bit louder than normal and that could be due to leaking camcover gasket.

If it's related to bearings you'll get low oil pressure as well as the knocking sound (hammer against metal bench type of sound and probably start off as a soft knocking sound and get louder as it gets worse). Testing oil pressure and comparing to factory manual figures is the only way that I know of to check for bearing wear without pulling engine apart to inspect them.

[Gibson]

Hmm, I'll keep an eye on the oil pressure ... I've got a gauge in the cabin. Are the lifters really loud from under the car? I can hear the noise very clearly if I'm listening through the front wheel well or lying under the car, not so much when I'm standing over the engine.

[Gibson]

Although actually now that you mention it, I think my cam cover gasket does have a slow leak that was found during my initial inspection of the car. How hard on the engine is it to run with a leaking cam cover gasket?

[Skym]

Aftermarket oil pressure gauge is more accurate (remove stock gauge oil pressure sensor, screw in oil pressure gauge, rev engine, etc), as stock oil pressure sensor (for stock oil pressure gauge) is usually clogged (some have cleaned the oil pressure sensor and it works like new) thus stock gauge reading is inaccurate.

From my experience, excessive lifter noise can be heard on the side of engine and was at back of engine on exhaust side (normal place where it leaks).

Symptoms of this leak is engine doesn't perform as it should (pickup), similar to a intake airleak. Also get excessive lifter noise where the leak is. The leak is usually related to the washers under the screws (failed), more than the cam cover gasket themselves.

Can buy a Permaseal camcover gasket kit that has gaskets for oil cap, camcovers x2, halfmoons x2, screw washers for a good price.

Permaseal gasket part numbers -

http://www.nzgaskets.co.nz/SetDetails.aspx?SetID=2418

[Gibson]

That definitely sounds like the issue, I'll get those replaced ASAP. Do you know how labour-intensive that job is?

Also is it safe to drive the car with a bit of a leak from there?

Thanks for the help, really appreciate it.

[Skym]

It's around 2-3 hours (from memory), but that depends on how fast you do it.

It just requires removing intake pipe over engine (including hoses, etc), remove coilpack cover screws in reverse sequence, remove coilpack cover, remove both camcovers in reverse sequence to the sequence you use to tighten the screws (so you don't warp the camcovers), remove halfmoons on back of head.

Fit new halfmoons with a little bit of liquid gasket (can buy from Nissan dealership) between head, halfmoons. Put some liquid gasket on front and rear of head where camcover gasket goes on left, right side of engine, fit camcovers with gaskets, washers, fit and tighten screws in sequence, refit the coilpack cover, tighten coilpack cover screws in sequence, refit intake pipe, hoses over engine, etc.

I think was 3-4nm for torque (double check this) for screws (cam covers), which is not much. Sequence is in the manual.

Worth it to buy a translated printed manual -

http://www.jpnz.co.nz/afawcs0131170/CATID=24/SUBID=273/page=1/products.html

Can drive around with it like that for a while (wouldn't recommend to). Just performance, oil leaking down side of block (fire hazard if exhaust manifold gets really hot) are the problems you'll encounter.

[Gibson]

Very cool, thanks for the information man. I'm still hoping it's just cause I overfilled the oil a little bit but the cam cover casket was something I needed to tackle sooner or later anyway.

Cheers

[99_SI]

My cam cover was leaking....untill i tightened the the bolts.